(6) The half life of a substance is the time it takes for a substance to decrease to half its initial amount. John has a pile of goo that decreases in amount at a constant rate. If John initially had 100 pounds of goo, and ten days later, he only had 25 pounds of goo, what is the half of the goo ?

(8) Jackie fills a jug with water continuously. It takes her 2 minutes to fill up 50% of the empty space in the jug with water. After every 2 minutes, she puts a penny into a jar to celebrate. How many pennies will she have in the jar at the instant the jug has less tan 30% empty space left ?